Figure
4.
Desulfurization
of 2-ethyl-1 -hexanethiol
5
UNKNOWN IMPURITY
E _I
Y
w 0 w 0
IBG
bond is weak, and, upon deoxygenation, that bond is broken preferentially to the carbon-oxygen bond. This is illustrated in panel l of Figure 3, where, at 138” C., n-heptane was the product from the deoxygenation of 2-ethyl-lhexanol. Raising the deoxygenation temperature favors increased yield of 3-methylheptane (panels 2 and 3), but at 300” C. (panel 4) a significant amount of n-heptane is still being produced and numerous minor peaks appear in the chromatogram, indicating that extraneous unidentified fragments also are being formed. Because equal mass samples of the deoxygenated products were not charged to the G-L chromatograph, the series of chromatograms of Figure 3 are not quantitatively comparable. Ho\yever, the ratio between the peak height of 3-methylheptane and that of n-heptane may be calculated and, over the range investigated, increases linearly with temperature from zero to 0.09. Temperatures above 300” C. have not been investigated, but extensive sample “cracking” probably will occur long before this ratio becomes much greater.
R. V, HELM,
I50
140
130
120
110 100 TIME, MINUTES
Hydrogenation of sulfur compounds having structures analogous to those of the last three oxygen compounds listed in Table I indicates that the sulfur compounds react “normally”-that is, split off the -SH radical with no detectable side reactions. For example, 2-ethyl-1-hexanethiol reacts in the following manner :
80
I
H1
cz
~
+- Cat.
C:-C-C
ID
0
hexanethiol, as that would imply isomerization or an increase in molecular weight upon desuifurization, phenomena not observed in the desulfurization of any other sulfur compounds (1). n-Heptane was not found in the desulfurized products, indicating that the reaction: Cd-Y-C-SH
2000 C.
C,-C-C-SH
20
-+
C:-C
I
I
Ca
does not occur Pertinent chromatograms are shown in Figure 4. The sample of 2-ethyl-Bhexanethiol contained a t least one impurity (emergence time, 86 minutes) which was easily excluded from the desulfurized sample and possibly two or three in the trapped material concealed under the large peak at 153-minute emergence time. The latter impurities are assumed because of the appearance in the chromatogram of the desulfurized material, of the extraneous peaks at 16.1 and 17.2 minutes. Material producing these peaks is not expected to have originated from the 2-ethyl-l-
LITERATURE CITED
N. J., Ward, C., Rall, H. T., ANAL.CHEW 32,424-30 (1960).
(1) Thom son, C. J., Coleman,
8.
RECEIVEDfor review April 28, 1960. Accepted August 15 1960. Sixth Qklahoma Tetrasectional keeting, ACS, Ponca City, Qkla., March 26, 1960. Investigation performed as part of American Petroleum Institute Research Project 48A on “Production, Isolation, and Purification of Sulfur Compounds and Measurement of Their Properties,” which the Bureau of Mines conducts at Bartlesville, Okla., and Laramie, Wyo.
D. R. LATHAM, C. R. FERRIN, and J. S. BALL
baramie Petroleum Research Cenfer, Bureau of Mines, Carbazole has been identified in Wilmington, Calif., petroleum--the first nonbasic nitrogen compound isoiated from virgin petroleum. A fraction of the appropriate boiling range reacted with sodium amide in liquid ammonia to give a concentrate of nitrogen compounds whish was further resolved by gas liquid chromatography. The
U. S. Department of the Interior,
material under one of the peaks gave mass, infrared, and ultraviolet Spectra which confirmed its identity as carbazole. Similar procedures on a concentrate of nitrogen compounds prepared by techniques designed to prevent thermal decomposition confirmed the presence of carbazole in a t least 2 p.p.m. concentration.
baramie, Wyoming
has been identified in Wilmington, Calif., crude oil and becomes the first nonbasic nitrogen compound to be isolated from a virgin petroleum. This identification, which was accomplished by American Petroleum Institute Research Project 52, was made by spectroscopic techniques on materials separated by two indeARBAZOLE
VOL. 42,
NO. 13, DECEMBER 1960
IT
ethylene bath; the flask wa8 fitted with a dry ice reflux condenses and a magnetic stirrer; metallic sodium (0.2 gram) and ferric chloride (0.01 gram) w r e added to the liquid ammonia; when the evolution of hydrogen stopped, air mas bubbled through the solution until the original blue color changed to brown-gray; and finally, a n additional 1.3 grams of metallic sodium was added and allowed to react until the color returned to brown-gray. The oilsodium amide mixture was refluxed with stirring for 2 hours and then the reflux condenser was removed, allowing the ammonia to evaporate. The material remaining was filtered, and the precipitate was repulped and washed several times with %pentane. The precipitate was hydrolyzed with distilled water, and the resulting solution was extracted consecutively with pentane and benzene. The combined extracts weighed 1.1 grams after removal of the solvents.
300' to 400' C. As this method may have caused thermal reaction to produce carbazole, the second method wa8 selected to minimize the possibility of thermal decomposition, and temperatures did not exceed 110' C. EXPERIMENTAL
Figure 1 .
A sample of Wilmington crude oil was deasphaltened with n-pentane (W), and the deasphaltened oil was used as the starting material for this investigation. During all operations, the oil was blanketed with nitrogen gas containing less than 2 p.p.m. of oxygen. Method I. T h e exploratory work to determine the presence of carbazole in the crude oil is outlined in t h e left column of Figure 1. Approximately 8 kg. of the deasphaltened oil was distilled in an all-glass system over a n $-hour period. Fourteen 25' C. cuts mere collected between 50" C. a t atmospheric pressure and 300' C. at 40 mm. (430" 6.at 760 mm.). The cuts boiling between 175" and 250" C. at 40 mm. (280" to 370" 6 , at 760 mm.) were combined and fractionally distilled in a 6-foot by 1-inch Stedman column. The pressure during the fractional distillation was controlled to maintain the pot temperature below 300" 6. The temperature to which the original oil had been exposed up to this point was estimated to be between 300" and 400" C. A 161-gram portion of the fraction boiling between 320" and 330" C. at 760 nim. was diluted with 100 mi. of n-pentane and added slowly to a solution of sodium amide in liquid ammonia prepared as follows: Approximately 500 ml. of ammonia was condensed in a 1liter flask, cooled in a dry ice-trichloro-
Separation of carbazole
pendent procedures. Carbazole was found to the extent of a t least 2 p.p.m. Two thirds of the nitrogen in crude oil is nonbasic, but only the basic portion had been investigated extensively (4)until API Research Project 52 was established in 1954 t0 study the nonbasic nitrogen compounds in virgin petroleum. A 1953 review of the literature ( 1 ) showed that nonbasic compounds such as pyrroles, indoles, and carbazoles had not been identified in straight-run petroleum distillates but that some of these compounds had been found in cracked materials such as coal tar distillates, shale oil, and cracked petroleums. Later work extended these findings to gilsonite distillates (8) and to catalytically cracked petroleum gas oils (6). Mass and ultraviolet spectral evidence for the presence of compounds of the carbazole type in straight-run and cracked petroleum distillates was reported ( 7 ) i n 1952, but no individual compound was identified. Lalau (3) also found carbazoles mass spectrometrically in "representative petroleum fractions." These fractions were unidentified as to source of oil and processing history. This paper describes the separation of carbazole from Wilmington crude oil by two methods. The first method subjected the oil to temperatures of
,
1
The low-voltage mass spectrum of this extract showed materials with molecular weights corresponding to carbazole (167) and Ci to Ce substituted carbazoles. A material having a molecular weight of 194 and its C1 to 6 4 homologs were contaminants in the extract. From these data the carbazole was calculated t o be approximately 1% of the extract and was estimated to be present in the crude oil to the extent of a t least 2 p.p.m. The extract was resolved using a gas chromatographic unit packed with Dow Corning high-vacuum silicone grease supported on Chroniosorb and maintained a t 250" C. The detector was shut off to minimize decomposition
V."
V
E-
2
a
ISOLATED F W M 320-33O'C FRACTION .bL-bLII 13 15 LENGTH MICRONS LENGTH.
MATERIAI
w 10 u u rn----, z z
~
7
9 WAVE
0
1
,
2.0 r M A T E R I A L ISOLATED F R O M
-CARBAZOLE
U
I
SOLVENT : E T H Y L ALCOHOL \
'---
0 240
260
280
WAVE
300 320 LENGTH, MILLIMICRONS
Figure 2. Ultraviolet identification from Wilmington crude oil
1766
e
ANALYTICAL CHEMISTRY
340
360
of carbazole
A-KEr
WAVE LENGTh, MICRONS B-Kl
PRESSED P L A T E
of
carbazole
MICROPRESSED P L A T t
Figure 3. Infrared Wilmington crude oil
identification
from
from the hot wire, and the extract was separated into several fractions on a time basis. The fraction corresponding to the emergence time of carbazole was collected in a dry ice trap. The carbazole concentrate collected was a white crystalline solid. A low-voltage mass spectrum of the carbazole concentrate showed that the carbazole had been concentrated 10 times that in the original extract material. The ultraviolet spectrum of the carbazole concentrate is shown in Figure 2 together with the ultraviolet spectrum of carbazole. The two spectra show four distinct absorption peaks a t 245, 258, 295, and 335 mp. The infrared spectrum of this sample was obtained using the potassium bromide micropressed plate technique described by Mason (6). This spectrum is shown in the upper curve of Figure 3. The lower curve shows the infrared spectrum of carbazole. Agreement between the spectra is seen a t wave lengths of 7.2, 7.5, 7.75, 8.05, 8.3, 10.75, 10.90, 11.65, 11.85, 13.2, 13.36, and 13.79 microns. These peaks are indicated by the arrows in the upper curve. The ultraviolet spectra establish the carbazole class of compounds, while
the infrared and mass spectra give positive proof of the presence of carbazole itself. Method 11. The procedure is shown schematically in the right column of Figure 1. The nitrogen concentrate was prepared by adsorption of the deasphaltened crude oil on Florisil (synthetic magnesium silicate) a t room temperature as described in a previous publication ( 2 ) . This concentrate was then distilled into four fractions and a residue in an all-glass molecular still. The maximum temperature during the collection of fraction 1 was 110" C., and the pressure was 0.04 micron The low-voltage mass spectrum of the first fraction showed the presence of conipounds having molecular weights of carbazole and C1 to Clo substituted carbazoles. Contaminants in the 194 molecular-weight series appeared as they had in the extract by Method 1. The first fraction was separated b y gas chromatography as described in Method 1. The low-voltage mass spectrum and the infrared spectrum obtained on this carbazole concentrate corresponded to those obtained on the carbazole concentrate by Method 1.
These data establish the presence of carbazole in Wilmington, Calif., crude oil. LITERATURE CITED
(1) Deal, V. Z., Weiss, F. T., Vhite, T. T., ANAL.CHEW25, 426 (1953). (2) Helm, R. V., Latham, D. R., Ferrin, C. R., Ball, J. S., Ind. Eng. Chem., Chem. Eng. Dataseries 2, 95 (1957). (3) Lalau, C., $rial. Chim.Acta 22, 23949 (1SfiO'i. ,- - - ,
(4)-Lochte, H. L., Littmann, E. R;: "The Petroleum Acids and Bases, Chem. Pub. Co., T e i v York, 1955. (5) Mason, W. B., "Infrared RIicrosampling in Bio-Medical Investigations," Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 1958. (6) Nixon, A. C., Thorpe, R. E., "Effect of Composition on the Stability and Inhibitor Response of Jet Fuels," Division of Petroleum Chemistry, 130th Meeting, BC8, Atlantic City, N. J., Sent,emher 19.56 _.r ....._. _._ _ _
(7) Sauer, R. W.,Melpolder, F. W., Brown, R. A,, Ind. Eng. Chent. 44, 2606 (1952). (8) Sugihara, J. &I., Sorenson, David, J . Am. Chem. SOC.77,963 (1985).
RECEIVED for review June 17, 1960. Accepted September 12, 1960. Division
of Petroleum Chemistry, 137th Meeting, ACS, Cleveland, Ohio, April 1960.
High Temperature Gas-Liqui Chromatography Exploratory Studies Using an Ionization Detector Chromatograph B. J. GUDZINOWICZ and W.
R. SMITH
Research and Engineering Division, Special Projects Deparfmenf, Monsanto Chemical
b Preliminary qualitative and quantitative investigations with an ionization detector chromatograph modified for high temperature operation have been completed. Lower molecular weight hydrocarbons and complex aromatic mixtures, with some components having boiling points above 500" C., were resolved and determined. The accuracy and precision of this instrument using microgram quantities of organics are comparable to results from conventional instruments.
I
N RECENT YEARS, greater emphaeis has been placed upon the use of chromatographic techniques in solving complex chemical problems. Aliphatic and aromatic heterogeneous mixtures with some individual components having boiling points above 300" C. have been separated. Thermistor and hotwire filament thermal conductivity detectors, previously considered adequate for the solution of nearly all conven-
tional research problems, are being challenged on a more competitive basis by instruments incorporating highly sensitive detectors designed on flame ionization, a- and ?-ray ionization, and radiofrequency principles. These detectors, v i t h reported eensitivities of 10-15 mole, coupled with capillary columns of 100,000 to 200,000 theoretical plates have provided an impetus to the application of gas chromatography to challenging analytical exploratory studies. Ogilvie, Simmons, and Hinds (16) explored the distribution of n-paraffins in waxes with a filament detector instrument of their own design operable a t 300" to 400" C. Dal Kogare and Safranski (8) developed a chromatographic unit for the 150" to 350" C. range incorporating platinum filament thermal conductivity detectors for the resolution of hydrocarbon, ester, and glycol mixtures. They (8) note that publication on high temperature ex-
Co., Everett,
Mass.
ploratory studies has been limited. Nevertheless, all authors point to the potentialities of high temperature gas chromatography (1, 6, 7 , 9, 19, 13, 17). Recently, Hudy (11) applied high temperature chromatography to resin acid methyl esters. Baxter and Keen (3) resolved aromatic hydrocarbons using polyphenyl tars from irradiated terphenyl mixtures as stationary liquid phases. Their upper operating temperature limit was 450" C. These polyphenyl tars, which have also been evaluated a t this laboratory, are outstanding contributions to high temperature chromatography. In many instances, they are preferable to snd more thermally stable than such immobile phases as Apiezon L, silicone grease, polyethylene, and asphaltenes (16).
Although work a t high temperatures has been performed by many laboratories with conventional thermal conductivity detector instruments, very VOL. 32,
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